Method of and apparatus for sterilizing and disinfecting articles



Dec. 10, 1968 K. A. o. WALLDEN 3,415,613

METHOD OF AND APPARATUS FOR STERILIZING AND DISINFECTING ARTICLES 4 Sheets-Sheet 1 Filed Sept. 20, 1963 INVENTOR KNUT ANDERS OSBORNE WALLE CARL LENNART JONSSON N, DECEASED LEGAL REPRESENTATNE Dec. 10, 1968 K. A. o. WALLDEN 3,

METHOD OF AND APPARATUS FOR STERILIZING AND DISINFECTING ARTICLES Filed Sept. 20, 1963 4 Sheets-Sheet 2 IN VENTOR KNUT ANDERS OSBORNE WALLEN,DECEASED CARL LENNART JONSSON LEGAL REPRESENTATIVE Dec. 10, 1968 K. A. o. WALLDEN 3,415,613

METHOD OF AND APPARATUS FOR STERILIZING AND DISINFECTING ARTICLES Filed Sept. 20, 1963 4 Sheets-Sheet 5 Fig. 3 6

INVENTOR KNUT ANDERS OSBORNE WALLENpECEASED CARL LENNART JONSSON LEGAL REPRESENTATIVE Dec. 10, 1968 K. A. o. WALLDEN 3,415,613

METHOD OF AND APPARATUS FOR STERILIZING AND DISINFECTING ARTICLES 4 Sheets-Sheet 4 F1 led Sept. 20

INVENTOR KNUT ANDERS OSBORNE WALLEN CARL LENNART JONSSON ,DECEASED LEGAL RE PRESENTATIVE United States Patent Office 3,415,613 Patented Dec. 10, 1968 3,415,613 METHOD OF AND APPARATUS FOR STERILIZING AND DISINFECTING ARTICLES Knut Anders Osborne Wallden, Kaptensgatan 1, Kungsbacka,,$weden Filed Sept. 20, 1963, Ser. No. 310,244 22 Claims. (CI. 21-56) ABSTRACT OF THE DISCLOSURE In an autoclave having a space for sterilizing and disinfecting articles, a source of supply of wet saturated steam which is at a pressure sufficient to eifect sterilization of the articles, flowing the wet saturated steam through an elongated path of flow which is outside the space, heating the saturated steam to an elevated temperature while flowing through the elongated path of flow to dry the saturated steam and reduce its humidity, flowing the dry saturated steam through a passageway from the elongatedpath of flow into a steam dispersing zone at the upper part of the space, heating the dry saturated steam while flowing through the passageway to maintain the steam at least at the elevated temperature, dispersing the dry saturated steam from the zone into the space, and heating the dry saturated steam at the dispersing zone to maintain the saturated steam therein at least at the elevated temperature, the heating of the saturated steam flowing through the elongated path of flow and the passageway and in the dispersing zone functioning to insure that the saturated steam dispersed from the zone into the space will be substantially devoid of humidity and superheat.

BRIEF SUMMARY OF THE INVENTION In hospitals it is necessary 'before an operation to sterilize all instruments, bandages and other equipment to be used for the operation. The sterilizing desirably must be carried out to such a degree that all contagious matter will be rendered innocuous. Mattresses, bedding, clothes and other articles which have been used by an infected patient must be disinfected before they can be used by another patient. Bacteriologists have probably less requirements for disinfection than for sterilization. The requirements for disinfection of bedding in hospitals must be increased, however, as of course no one can know which kind of bacteria-(spores) is present in the clothes and the bedding of the infected person.

In hospitals for patients with infectious-diseases, Formalin chambers are commonly used for this purpose. However, Formalin has a very low destructive eifect on bacteria. For this reason it has been necessary to disinfect articles by steam.

The best medium now known for sterilizing articles is saturated steam. The saturated steam has the quality that on condensing it emits latent heat and it is this heat that kills the bacteria. superheated steam or hot air does not possess this property. For sterilizing with superheated steam or hot air, the temperature must be at least 200 C. to 225 C. and the time necessary for sterilizing articles is 8 to 10 times longer than that required with saturated steam. When using superheated steam or hot air, the bacteria are destroyed by burning. Superheated steam or hot air cannot be used for bedding and other textile materials as, at the high temperatures at which these media are employed, the textile materials are damaged.

Common saturated steam contains considerable amounts of water (humidity). The water in the steam does not contain any latent heat and is thus of no use for sterilization and is to be considered a disadvantage. The water retards the sterilization and increases the humidity of the articles undergoing sterilization. The humidity in saturated steam often can be very high and, considering the condensation efiected in the piping leading to the sterilizing chamber, at the start of a sterilization period a shower of condensate is obtained in the chamber together with the wet steam.

The sterilization is a function of time and temperature. The required treatment time depends on the goods to be treated. As the articles to be sterilized often comprise textile materials and .rubber goods, the temperature should not exceed 142 C. When such a high temperature is used, the duration of the treatment should be rather short for otherwise the goods to be sterilized can be completely decomposed and destroyed.

Sterilizing by saturated steam is principally rather simple. On the other hand, it has hitherto been diflicult to dry the goods after the sterilizing operation. It is as important for the goods to be dry after sterilization as it is for the goods to be sterilized by the treatment, as wet goods readily absorbs bacteria.

For sterilizing mattresses, pillows (down cushions) and similar articles, for example, the problem of keeping the goods undergoing sterilizing dry is even greater than when sterilizing articles like bandages, for example. If a mattress becomes very wet, it will take a considerable length of time to dry it. The mattress will often be completely destroyed and this is probably the reason why hospitals and similar institutions seldom sterilize or disinfect mattresses, pillows and other bed eqiupment. This problem has been very difiicult to solve.

For sterilizing articles, a steam pressure of at least 1 to 3 kg./cm. is often used which corresponds to a temperature of about 119 C. to 143 C. A lower steam pressure usually is employed with older autoclaves. As the goods undergoing disinfection as a rule cannot withstand this high temperature, a pressure higher than 1 kg./cm. (119 C.) usually is not employed. This steam pressure (temperature) is frequently employed for sterilizing articles like mattresses and down cushions for example. The ideal steam {temperature should not exceed C. to 106 C. which corresponds to a steam pressure of about 0.3 kg./cm. At lower steam temperatures the length of time of the sterilizing period will be unduly long.

The object of this invention is to overcome the aforementioned drawbacks and this is obtained by using dry saturated steam in an autoclave for the sterilization or disinfection of articles. It has been found that dry saturated steam has a much higher ability to penetrate articles undergoing sterilization than steam having a relatively high amount of humidity. By treating goods undergoing sterilization with dry, saturated steam, the duration of the treatment is shortened considerably. When the steam comes into contact with the goods, it emits its latent heat by condensation. This heat of condensation takes place continuously and continues until the goods has been completely penetrated by the dry saturated steam and its temperature has been raised to that of the steam enveloping the goods. When dry saturated steam is employed the humidity in the goods will be the same as that of the steam which is condensed in the goods. 0n the other hand, if the steam should have a greater or smaller humidity and is not dry, the humidity of the goods will then be higher than that of the condensed steam. This additional humidity will delay the sterilization operation and presents difficulties in connection with the subsequent drying of the goods. This is especially true for mattresses and other bedding, for example.

After sterilization or disinfection, the treated goods are subjected to vacuum for removal of the humidity and drying. The amount of heat contained in the goods is exactly the same as that emitted from the steam in the form of latent heat by the condensation of the dry saturated steam. When the saturated steam introduced into the sterilization chamber is dry, the humidity in the goods undergoing sterilization is quickly evaporated. On the other hand, when wet steam is employed to sterilize the goods, the latter will not be dried as the wet steam does not contain a sufiicient amount of heat to effect evaporation. This has been the main problem in hitherto known methods.

Proposals have been made to effect sterilization by dry saturated steam, but for difierent reasons the desired results have not been attained. However, the present invention gives a satisfactory solution to this problem. The main feature of the invention is that humid saturated steam of higher pressure thanithat intended for sterilization is fed through suitably tube-shaped channels in a steam chamber and through a sprayer tube for heating the latter, that the steam pressure is reduced to sterilization steam pressure, and that the steam at the lower pressure is fed through the steam chamber and dried by coming in contact with the walls of the tube-shaped channels heated to a higher temperature at the same time that a control valve is heated by the steam at the lower pressure, and that finally the dried steam is fed through the control valve and the sprayer tube into the sterilization chamber.

The invention also includes an autoclave for practicing the method described above.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING My invention will now be described with reference to the accompanying drawing. In the drawing:

FIG. 1 is a vertical sectional view taken lengthwise of an autoclave embodying the invention;

FIG. 2 is a transverse vertical sectional view of the autoclave shown in FIG. 1;

FIG. 3 is a horizontal sectional view taken on line III-III in FIG. 1; and

FIG. 4 is an enlarged view, partly in section, of details shown in FIGS. 1 and 2.

DETAILED DESCRIPTION The autoclave shown in FIGS. 1 to 4 is carried by a stand 1. The sterilization chamber 2 of the autoclave at its ends is provided with openings 3 and 4, respectively, which can be closed by doors or closures 5 and 6, respectively. The articles to be sterilized, such as mattresses, for example, may be introduced through the opening 3 into the chamber 2, and, after being sterilized, may be removed from the chamber 2 through the opening 4.

The sterilization chamber 2 is defined by a bottom 7, side walls 8 ahd a roof 9 provided with external reinforcing bars 10. An outer mantle is arranged to form a steam chamber about the sterilization chamber 2. This last-mentioned steam chamber is divided by a partition 12. into a lower steam chamber 13 extending below the bottom 7 and outside the side walls 8 and a steam chamber 14 extending above the roof 9. The two steam chambers 13 and 14 are in communication with one another through a number of apertures 12a in the partition 12. In the upper steam chamber 14 are provided two groups of elongated parallel tubes 15 through which axially extend steam tubes 16. The tubes 15 are connected in series relation by end connections 17 and 18 and each group of tubes 15 is connected to a single main valve 19 which is common to the two groups of tubes. The valve 19 is positioned in the upper steam chamber 14 and heated by the steam flowing through that chamber in heat exchange relation with the valve 19. The valve 19 is provided with an outlet 20 connected to a steam diffuser tube 22 which has steam diffuser apertures 21 and extends lengthwise of the sterilization chamber 2, as shown in FIG. 1. A guide wall 23 of helical form extends about and lengthwise of each tube 16 and is disposed in the radial gap between the steam tube 16 and the tube 15 extending lengthwise of and enveloping the tube 15. The ends of the steam tubes at one side of the autoclave are connected to a manifold or distribution tube 24 for steam introduced therein at a definite high pressure, as best seen in FIG. 3. The steam tubes 16 at the opposite side of the autoclave are connected to a tube 25 from which an exhaust tube 27 extends downward and at its lower end is provided with a condensate drain tube or escape 26, as shown in FIG. 21. The tube 25 is connected by a conduit 28 to one end of a tube 29 which extends lengthwise of and within diffuser tube 22, as shown in FIGS. 2, 3 and 4. As shown in FIG. 4, a tube 31 extends lengthwise of and within the diffuser tube 22 and is disposed about the tube 29, the tubes 29 and 31 having a radial gap 30 of annular form therebetween. The steam flowing in one direction through the tube 29 passes into a closed end chamber 30a formed at the end of the tube 31 and then flows in the opposite direction through the gap 30, which functions as a return passageway, to a conduit 32, as seen in FIGS. 3 and 4. The conduit 32 is connected to a pressure reducing valve 33 and steam at a lower pressure flows therefrom through a conduit 34 which is connected to a longitudinal diffuser tube 35 which has a plurality of exhaust apertures 36 for the steam and is disposed in the lower steam chamber 13.

All of the tubes 15, with the exception of the outer ones in each group, are closed at both ends. Each of the two outer tubes 15 is open at one end opposite the other end which is connected to one of the connecting tubes 17 (FIG. 3).

The lower steam chamber 13 is provided with an exhaust tube 37 having a condensate outlet 38 at its lower end. Also, the sterilization chamber 2 at the bottom 7 is provided with a downward extending tube 39 having a condensate discharge 40 at its lower end. Further, the tube 39 is provided with a connection 41 connected to a vacuum pump 41 1.

Before describing the sterilization process, it is desirable to explain the manner in which the saturated wet steam, which is introduced from a suitable source of supply (not shown) into the inlet manifold or distribution tube 24 at the arrow A in FIG. 3, is dried before it is allowed to enter the sterilization chamber 2. When the steam flows through the tubes 16 to the outlet manifold or steam collecting tube 25, the helical wall 23 is heated and so are the tubes 15. The steam from tube 25 passes through conduit 28 and thereupon flows through the tubes 29 and 31 in the manner explained above and heats the diffuser tube 22. After the steam pressure is reduced in the valve 33, the steam at a lower pressure flows out through the openings 36 in the diffuser tube 35 into the lower steam chamber 13 and then passes upward through the openings 12a in the partition 12 into the upper steam chamber 14. Water condensate formed in the upper and lower steam chambers 14 and 13 escapes through the condensate drain tubes 26 and 38, respectively. The steam passing into the upper steam chamber 14 flows into the open end of each of the outer tubes 15 of the tube groups, as indicated by the arrows 42 in FIG. 3, and passes through the tubes 15 in which the steam, due to the shape of helical walls 23, is forced to flow in a helical fashion around the longitudinal axes of the tubes 15 which provides elongated paths of flow for the steam which are in intimate heat exchange relation with the steam flowing through the heating tubes 16. From the tubes 15 of the two groups which are nearest to one another, as shown in FIG. 3, the dried saturated steam flows through conduits 15a to the valve 19. The tubes 15 connected in series define an elongated path of flow for the saturated steam to be dried and heating of the saturated steam lengthwise of the elongated path of flow is effected at least at axially extending regions thereof which are formed by the tubes 15 and are distributed throughout the entire length of the elongated path of flow between the inlets 42 and the outlets at the region at which dried saturated steam flows into the inlet ends of the conduits 15a forming part of a passageway leading to the diffuser 22 in the upper part of the space 2. The valve 19 is opened and closed by its control member 19:: which is accessible outside the autoclave. When the control member 19a is moved to open valve 19, dried saturated steam can flow through the passageway which includes the conduits 15a and the valve 19 and pass from its outlet 20 and flow int-o the preheated diffuser tube 22, as best shown in FIG. 4. The dried saturated steam is discharged from the diffuser tube 22 through the apertures 21 into the sterilization space 2. The same pressure prevails in the sterilization chamber 2 that prevails in the lower and upper steam chambers 13 and 14. However, the main valve 19 may be controlled by a thermostat (not shown) for operating the autoclave in such manner that a lower pressure (temperature) will be maintained in the sterilization chamber 2 than in the two steam chambers 13 and 14. The pressure reduction valve 33 functions to determine the pressure in the steam chambers 13 and 14. On the other hand, the main valve 19 may be used to determine the pressure (the temperature) in the sterilization chamber 2. The last mentioned pressure (temperature) in the sterilization chamber 2 either will be equal to or lower than the pressure (temperature) in the steam chambers 13 and 14. The pressure of the steam introduced and supplied to the inlet manifold or distribution tube 24 will be maintained at such a value that the dried saturated steam entering the sterilization chamber 2 will not be superheated.

By sterilizing articles in the chamber 2 with dry saturated steam it is possible to use steam at a lower pressure than when using wet steam without unduly lengthening the sterilization time. For disinfecting articles, a pressure of about 0.3 kg./cm. which corresponds to a temperature of about 106 C., is sufficient. This is most advantageous because surgeons presently often use articles which will not withstand a temperature exceeding 110 C. to 115 C.

When the sterilization chamber 2 has reached a predetermined pressure, this pressure desirably is maintained during the time required to effect complete sterilization or disinfection of the goods. However, the air in the autoclave must be withdrawn before sterilization of articles can be effected. Since the specific gravity of steam is lower than that of air, the steam is employed to evacuate the air from the sterilization chamber 2. A suitable program for sterilizing articles is described hereinafter, as follows:

(a) Steam is fed to the chamber 2. The air is evacuated through the tube 39 by the vacuum pump 41a. When the air is completely evacuated from the chamber 2 and the temperature in the sterilization chamber 2 increases, the vacuum pump 41a is rendered inoperable. The pressure and temperature in the chamber 2 increases to a predetermined value. The first evacuation of air from the chamber 2 is terminated.

(b) The steam inlet to the chamber 2 is now closed by operating the control member 19a of the valve 19 and the vacuum pump 41a is started. The pressure in the sterilization chamber 22 will be decreased as close as possible to an absolute zero pressure or vacuum. When sterilization of textile material is being effected this operation is necessary to insure that all of the air will be evacuated from the textile material.

(c) The vacuum pump 41a is stopped and the valve 19 is then opened. The pressure and temperature in the chamber 2 are allowed to increase to a value which is predetermined for the particular sterilization being effected and the goods in the chamber are sterilized.

(d) When sterilization of the goods has been completed, the valve 19 is closed and the vacuum pump 41a is again operated. The humidity is removed by evaporation and drying of the material is effected. When dehumidi-fication of the material is completed, air can he introduced into the sterilization chamber 2 and the closures 5 and 6 can then be opened and the sterilized goods can be removed from the autoclave.

The program just described may be employed for the sterilization or disinfection of beddings and the like, for example. For the sterilization of surgical instruments Steps b and c can be omitted.

As just described and shown in the accompanying drawing, wet saturated steam is dried by steam at a higher pressure and temperature and the dried saturated steam is introduced into the sterilization chamber 2.

The present invention has been described in detail for purposes of illustration only. Modifications are possible within the scope of the invention and it may be advisable to shape the autoclave as a hollow cylinder as cylindrical walls offer a better resistance to the negative or positive pressures developed in the sterilization chamber.

What I claim is:

1. A method of sterilizing and disinfecting articles in a space which comprises the steps of:

(a) maintaining a source of supply of wet saturated steam at a first pressure sufiicient to effect sterilization of the articles and at a first tempearture,

(b) flowing the wet saturated steam from the source of supply to a first place to provide a body of the wet saturated steam in said first place,

(0) flowing the wet saturated steam from said first place through an elongated path of flow which has an inlet and an outlet and is out of physical contact with and enveloped by the body of wet saturated steam in said first place,

(d) heating the saturated steam to an elevated temperature which exceeds said first temperature while flow ing through said elongated path of flow effecting said last-mentioned heating lengthwise of said elongated path of flow between said inlet and outlet to dry the saturated steam and reduce its humidity,

(e) flowing the dry saturated steam through a passageway from said outlet of said elongated path of flow and out of said first place into a steam dispersing zone at the upper part of said space and dispersing the dry saturated steam into said space at said zone,

(f) heating the dry saturated steam while flowing through said passageway by the body of saturated steam in said first place the steam flowing through said passageway being out of physical contact with and enveloped by the body of saturated. steam in said first place, and

(g) heating said dispersing zone at a region which is in heat exchange relation with and out of physical contact with the dry saturated steam flowing to said dispersing zone from said passageway,

(h) the heating of the saturated steam flowing through said elongated path of flow and said passageway and in said dispersing zone functioning to insure that the saturated steam dispersed from said zone into said space at the upper part thereof will be substantially devoid of humidity and superheat.

2. The method set forth in claim 1 which includes the steps of controlling the flow of dry saturated steam through said passageway to the dispersing zone at the upper part of said space, evacuating fluid from the bottom part of said space, and regulating the evacuation of fluid from the bottom part of said space.

3. The method set forth in claim 1 which further includes the steps of i (a) providing a source of supply of vaporous fluid at a second pressure which is higher than the first pressure and at a second temperature higher than said first temperature, and

(b) flowing such vaporous fluid out of physical contact and in heat exchange relation with the saturated steam flowing through said elongated path of flow to heat the saturated steam to dry the latter and reduce its humidity.

4. The method set forth in claim 3 in which the vaporous fluid at the second higher pressure and second higher temperature, after functioning to heat the saturated steam flowing through said elongated path of flow in said first place to dry the latter and reduce its humidity, flows in heat exchange relation and out of physical contact with the dried saturated steam in said dispersing zone.

5. The method set forth in claim 4 in which the vaporous fluid at the second higher pressure and second higher temperature comprises saturated steam and further includes the steps of:

(a) reducing the pressure of the saturated steam from the second higher pressure to the first pressure and from the second higher temperature to the first temperature after the saturated steam at the second higher pressure and second higher temperature flows in heat exchange relation and out of physical contact with the dried saturated steam at the first pressure at said dispersing zone,

(b) enveloping said elongated path of flow in said first place by a body of the saturated steam at the first pressure, and

(c) flowing the last-mentioned saturated steam at the first pressure from said body in said first place to the inlet of said elongated path of flow.

6. The method set forth in claim 5 in which at least a part of said passageway in said first place is enveloped by said body of saturated steam at the first pressure, said body of saturated steam at the first pressure in said first place being in heat exchange relation and out of physical contact with saturated steam in said passageway.

7. The method set forth in claim 6 which includes the step of controlling the flow of saturated steam in said passageway from a region accessible outside of said space and said first place.

8. The method set forth in claim 6 in which, after the saturated steam is reduced from the second higher pressure to the first pressure, the space is enveloped by a blanket of the saturated steam at the first pressure which includes the body of saturated steam at said first place.

9. The method set forth in claim 8 in which the blanket of steam at the first pressure includes a first part which envelops the bottom portion of said space and a second part which envelops the top portion of said space, the second part of said blanket of steam defining said body of saturated steam in said first place which envelops said elongated path of flow of said saturated steam at the first pressure and at least said part of said pasasgeway of said saturated steam.

10. Apparatus for sterilizing articles comprising:

(a) structure defining a chamber for sterilizing articles therein and a housing having a first compartment,

(b) means providing a first source of supply of wet saturated steam at a first pressure sufficient to effect sterilization of the articles in said chamber and at a first temperature,

(c) an elongated hollow member in said first compartment having an inlet therein and an outlet,

((1) means for conducting said wet saturated steam at the first pressure and first temperature from the first source of supply to said first compartment to form a body of the saturated steam therein, said wet saturated steam in said first compartment flowing through said elongated hollow member from the inlet to the outlet thereof,

(e) first means extending lengthwise of said elongated hollow member for heating to an elevated temperature exceeding said first temperature the saturated steam flowing therethrough to dry the steam and reduce its humidity,

(f) an apertured diffuser disposed in the upper part of said chamber,

(g) conduit means for conducting the dry steam from the outlet of said elongated member to said apertured diffuser for discharging steam at the elevated temperature therefrom into said chamber, and

(h) second means in heat exchange relation with said di'lfuser for heating the saturated steam therein to at least said elevated temperature,

(i) said first and second means functioning to insure that the saturated steam discharged from said apertured diffuser into said chamber will be substantially devoid of humidity and superheat.

11. Apparatus as set forth in claim 10 in which said conduit means for conducting the dry saturated steam from the outlet of said elongated member to said diffuser includes a part in said first compartment which is enveloped by the body of saturated steam therein, said enveloping body of steam being in heat exchange relation and out of physical contact with saturated steam conducted through said conduit means.

12. Apparatus as set forth in claim 11 in which said part of said conduit means comprises a valve having a control member which is accessible outside the apparatus.

13. Apparatus as set forth in claim 12 which further includes means for evacuating fluid from the bottom of said chamber, and means for controlling said evacuating means.

14. Apparatus as set forth in claim 10 which further includes:

(a) means providing a second source of supply of wet saturated steam at a second pressure and second temperature higher than the saturated steam at said first pressure and said first temperature, and

(b) first means extending lengthwise of said hollow member and including first connecting structure for flowing wet saturated steam at said second pressure and at said second temperature from said second source of supply in heat exchange relation and out of physical contact with said saturated steam flowing through said elongated hollow member for heating the saturated steam therein to said elevated temperature.

15. Apparatus as set forth in claim 14 which further comprises second means including second connecting structure connected to receive wet saturated steam at said second pressure and said second temperature from said first connecting structure of said first means, said second connecting structure of said second means functioning to flow saturated steam at said second pressure and said second temperature in heat exchange relation and out of physical contact with saturated steam flowing in said diffuser before it is discharged therefrom into said chamber.

16. Apparatus as set forth in claim 15 which further comprises conduit means including pressure reducing valve means having high and low pressure sides for conducting saturated steam at the second pressure and the second temperature from said second connecting structure at said diffuser to the high pressure side of said pressure reducing valve means, the low pressure side of said pressure reducing valve means constituting the first supply of wet saturated steam at the first pressure and the first temperature.

17. Apparatus as set forth in claim 16 in which said housing further includes a second compartment, said first and second compartments being in communication with one another and enveloping said chamber, said second compartment being disposed about a lower part of said chamber and said first compartment being disposed about the upper part of said chamber, and said conduit means including said pressure reducing valve means including a connection from the low pressure side of said pressure reducing valve means to said second compartment for con ducting thereto saturated steam at said first pressure and said first temperature.

18. Apparatus as set forth in claim 14 in which said elongated hollow member includes a plurality of straight conduit sections and connecting bends, first and second manifolds, said first connecting structure including said first manifold, means for connecting said first manifold to the second source of supply of saturated steam, said first means extending lengthwise of said elongated hollow member including a plurality of straight tubular members having their opposite ends respectively connected to said first and second manifolds, and each of said tubular members being in good thermal relation with a different one of straight conduit sections.

19. Apparatus as set forth in claim 18 in which each of said-tubular members extends lengthwise of and within a different one of straight conduit sections.

20. Apparatus as set forth in claim 18 in which said second connecting structure of said second means includes said second manifold and a connection therefrom to said apertured diffuser for flowing saturated steam at said second pressure and said second temperature in heat exchange relation and out of physical contact with saturated steam in said difiuser which is discharged therefrom into said chamber.

21. Apparatus as set forth in claim 20 in which said diffuser includes an outer apertured tubular member having an inlet for receiving dry steam conducted thereto by said conduit means from said straight conduit section defining the outlet of said elongated hollow member, a first tubular member within said apertured tubular member and spaced therefrom, a second tubular member within said first tubular member and spaced therefrom, said connection from said second manifold being connected to said second tubular member at one end thereof, the opposite end of said second tubular member being in communication with one end of said first tubular member, and the other end of said first tubular member having an outlet for saturated steam at said second pressure and said second temperature.

22. Apparatus as set forth in claim 21 which includes conduit means connected to the outlet of said second tubular member which includes pressure reducing valve means having high and low pressure sides, said last-mentioned conduit means conducting saturated steam at said second pressure and said second temperature from said diifuser to the high pressure side of said pressure reducing valve means, the low pressure side of said pressure reducing valve means constituting the first source of supply of wet saturated steam at said first pressure and said first temperature.

- References Cited UNITED STATES PATENTS 1,398,503 11/1921 Dunham 2l-56 FOREIGN PATENTS 6,875 1905 Great Britain.

JAMES H. TAYMAN, JR., Primary Examiner.

US. Cl. X.R.

Ill-94, 98; 122459 

